US Director of National Intelligence Dan Coats today sidestepped questions about an explosive report which said President Donald Trump pressured him to help push back against the probe into Russian ties with his campaign.

Trump, according to the Post and confirmed by CNN, phoned the Director of National Intelligence Dan Coats and National Security Agency Director Adm. Michael Rogers after then-FBI Director James Comey publicly revealed before the House Intelligence Committee on March 20 that the FBI had an investigation underway into possible collusion to influence the 2016 election.

Coats and Rogers refused to comply with the requests, which they both deemed to be inappropriate, according to two current and two former officials, who spoke on anonymity.

The shortly after former FBI director James Comey announced the investigation into any links between Trump's campaign and Russian Federation.

The unusual request was written in a memo by Comey, who kept meticulous notes on his meetings with Trump.

"I made it clear in my confirmation hearing that my role in the role of the Director of National Intelligence is to provide intelligence information relevant to policy makers, so they can base their judgment on that".

There's the report that broke late last week - which the White House has not denied - of Trump telling the Russian foreign minister and Russian ambassador to the United States, "I just fired the head of the Federal Bureau of Investigation".

Both Coats and Rogers were uncomfortable with Trump's request, The Post's sources said.

If Mueller's investigation centers on obstruction of justice and the matter becomes a criminal one, Comey will likely become Mueller's central witness and his public engagement with Congress could be limited.

Senior intelligence officials also saw the March requests as a threat to the independence of United States spy agencies, which are supposed to remain insulated from partisan issues.

Trump's requests were perceived as an effort to discredit the FBI investigation, with a senior NSA official documenting Trump's conversation with Rogers in an internal memo (it is unclear whether the DNI office did something similar for Trump's conversation with Coats).

Ultimately, Trump chose to nominate Coats, rather than Rogers.

Justice Department ethics experts Tuesday cleared Robert Mueller to lead the Russian Federation probe, The Washington Post reported. Marco Rubio for president before backing Trump in May 2016.In short, Mr Comey, a practising Catholic of Irish origin, tried to prove himself being his own man - independent, not necessarily loyal to the elected president - the trait that cost him his job and led him to an undignified exit from one of the most significant positons of the government.

Trump responded by saying that he had the "absolute right" to share facts pertaining to terrorism and airline flight safety with the Russian officials. Comey claims the president directed him to forego an investigation into Michael Flynn, Trump's former national security adviser.

Ultimately, Trump made a decision to nominate Coats, rather than Rogers. Two days after tapes of this conversation were released, Republican leaders went to the White House and told Nixon that for the good of the country - and to avoid the personal embarrassment of impeachment - he must resign the presidency.